Water-treating composition



March 19, 1946.

F. E. HUBBARD ET AL 2,396 918 WATER-TREATING COMPOS ITION Original Filed Nov. 4, 1938 FKGURE Z F'. EHUBBRRD AND GR. MC CULLOUGH.

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ATTORNEY Patented Mar. 19, 1946 2,396,918 \VATER-TREATING COMPOSITION Findley E. Hubbard and Campbell R. McCullough,

Anniston, Ala., assignors to Monsanto Chemical Company, a corporation of Delaware Original application November 4, 1938, Serial No. 238,926. Divided and this application May 2, 1941, Serial No. 391,504

9 Claims.

This application is a division of our copending application Serial No. 238,926, filed November 4. 1938.

This invention relates to aggregated or agglomerated phosphate pro-ducts and particularly to such products having a high solution rate.

One object of the present invention is to provide an aggregated metal polyphosphate in a form possessing a rapid rate of reaction. A further object is the provision of a phosphate product in convenient form for water treating purposes. A still further object is to provide a nonsegregable dehydrated phosphate product in form suitable for reaction with water to produce solutions thereof.

One of the difficulties attending the solution in 4 water of the alkali metal meta or polyphosphates is the tendency of such phosphates, when added to water to become sticky and gummy and therefore to have a relatively low rate of solution in water. When this occurs dissolving becomes extl'emely slow and difilcult even though stirring is resorted to. In this connection it has already been proposed to press molten metaphosphates into thin flakes which were then subsequently coated with alkali metal salts. Such flaked product displays an improved solution rate over that of the original material but in most cases the rate is still so slow as to be objectionable for many applications.

We have now found that the alkali metal metaphosphates or polyphosphates if first reduced 'to powder form can be aggregated by means of moisture into small irregular granules or aggregates. which when added to water quickly fall apart and dissolve rapidly. The effect of our treatment is to provide a granular phosphate for convenience in' handling etc., while at the same time retaining the rapid solution of the individual particle of which the granule is composed.

We prefer to effect aggregation of the powdered alkali metal meta or polyphosphates by developing upon the surface of the powder particles of a film of sticky material. Such sticky material is preferably obtained upon the surface of the powder particles by exposing the same to water or water vapor, or by coating the particles with some sticky material. After the particles of the powder have been so treated they are agitated by revolving in a drum or stirred in a suitable manner. This treatment causes the particles of powder to agglomerate into larger granules which may then be made to have a considerable size. Before, during or rior to the process of aggregation described we may add other powdered salts to the powdered alkali metal metaphosphate or polyphosphates. By combining several salts in this manner with the meta phosphate, a variety of products suitable for various uses may be produced.

In spite of the size of the granules produced by the herein described process, the rate of solution is apparently greater than that of the original powder of which the granules are produced. This is so because of the shape of the original particles and the method of attachment of the particles to each other.

Figure 1 shows a reproduction of a microphotograph of the original particles, enlarged times, of the so-called sodium hexametaphosphate before having been aggregated as herein described. The material here represented had been screened to pass 80 mesh screen.

Figure 2 shows a microphotograph, enlarged 20 times of the aggregated granules of our product. This material has been screened to pass a 16 mesh screen and remain on a 50 mesh screen.

The individual agglomerated granule here shown in Figure 2 on theaverage contains between and 1500 of the discrete particles shown in Figure 1. These limits may be altered by a change in size of the granule or by change in size of the particle to the extent that each granule will contain from 25 to as many as 3000 particles per granule. Each aggregate-has a very irregular outer surface, as shown in Figure 2, and possesses considerable porosity because of the irregularity of the individual particles composing the granule.

Because of the inherent porosity possessed by the polyphosphate granule the rate of solution is enormously increased.

One of the difliculties' attending the process of dissolving the alkali metal polyphosphates, especially those polyphosphates containing considerable quantities of equivalent metaphosphate is the fact that when the ordinary form of such polyphosphate is poured into water there is formed a very viscous solution immediately in contact with the surface of the polyphosphate with the result that diffusion through such film is very slow and the solution process is time cons-uming.

Our new product on the other hand, has the property of dissolving very rapidly when dropped into water. Granules such as we have shown in Figure 2 when dropped into water descend for approximately 4 to 8 inchesand then disintegrate into the discrete individual particles due to the dissolving of the soluble bond between them and V larly shaped porous pletely without the usual difllculties hitherto encountered. The metaphosphates or polyphosphates referred to-are the type that are readily soluble in water and have the ability of reacting orcombining with calcium to soften water.

The polyphosphates may be thought of as products corresponding to the union of meta and pyrophosphates or their equivalent ortho salts,

for example, for the sodium salts.

NMPQO7+NaPOa NaaPa01o=Triphosphate NaiPzO1+2NaPOr NasPiom=Tetraphosphate Na4Pz0z+8NaPOz- NaizPmO:1=Decaphosphate Various alkaline salts may be incorporated into thmmetaphosphate or polyphosphate compositions. Such salts serve as adjusting agents to change the alkalinity of the solutions obtained, which may accordingly be adjusted either to a higher or a lower level. We contemplate the addition of such compounds as caustic soda or sodium sulphate or sodium bisulfate, bisulphite, soda ash, sodium bicarbonate, sodium meta silicate, soaps, trisodium orthophosphates, sodium pyrophosphates or mixtures of these. The corresponding potassium salts may also be used if desired.

The following examples will serveto illustrate the various products which may be produced according to our invention.

Example I Mix together-90 parts of dry hexametaphosphate (Na-P03) a, ture containing equal weights of sodium carbonate and bicarbonate. Charge the mixture into a horizontal rotating drum and humidify with air'saturated with water at.60 C. After a few minutes the material is discharged from the drum, screened and then may be dried. The product produced is free flowing and is rapidly soluble in water and will consist of irregularly -80 mesh sodium parts of a mix- .shaped porous granules comprised of loosely adhering solid particles. varied as desired.

Example II Mix together 85 parts of -80 mesh sodium tetraphosphate Na6P40l3 and parts of finely divided soap. Humidity and agglomerate as in Example I. The product will consist of irregugranules individually consisting of loosely adhering solid particles of so-- dium tetraphosphate interspersed with soap particles the whole having an exceptionally rapid solution. rate.

The proportions may be varied as desired. 7

Proportions may be Example III Example IV Mix together so parts of dry 40 mesh sodium hexametaphosphate, v 10 parts of tetrasodium pyrophosphate, Nli'PaOv, and 10 parts of a mix- -hexametaphosphate, 10 parts ture containing equal parts by weight of sodium carbonate and bicarbonate. glomerate as in Example I.

Example V Mix together 80 parts of dry -80 mesh sodium of crystalline disodium phosphate and 10 parts or sodium carbonate or bicarbonate. Agglomerate by the application of heat while rotating. Proportions maybe varied as desired.

Having now particularly described our inven- 7 tion and the manner 01' working the same we dethereupon screening sire not to be limited herein except as indicated by the prior art or as particularly pointed out by the following claims.

What we. claim is:

'1. Themethod or making a water treating product which comprises humidiiying powder particles essentially comprising a polyphosphate selected from the group consisting of alkali metal triphosphates, tetraphosphates and decaphosphates, agitating said humidified powder particles to form agglomerates therewith and thereupon screening and drying said agglomerates.

2. The method of making a water treating product which comprises humidifying powder particles essentially comprising a polyphosphate selected from the group consisting of sodium triphosphate, sodium tetraphosphate, and sodium decaphosphate, agitating said humidified powder particles to form agglomerates therewith and thereupon screening and drying said agglomera es.

3. The method of making a water treating product which comprises humidifying powder particles essentially comprising sodium triphosphate, agitating said humidified powder particles to form agglomerates therewith and thereupon screening and drying said agglomerates.

4. The method of making a water treating product which comprises humidifying powder particles essentially comprising sodium tetraphosphate, agitating said humidified powder particles to form agglomerates therewith and and drying said agglomerates.

5. The method of making a water treating product which comprises humidifyin-g powder particles essentially comprising sodium decaphosphate, agitating said humidified powder particles to form agglomerates therewith and thereupon screening and drying said agglomerates.

6. A water treating product consisting essentially of porous agglomerates composed of a number of irregularly shaped, loosely adhering, powder particles essentially comprising a polyphosphate selected from the group consisting of sodium triphosphate, sodium tetraphosphate and sodium decaphosphate, said particles being bound together to form said agglomerates by means of a humidified sticky film of said polyphosphate, said agglomerates being characterized by having the property of rapidly disintegrating into finely divided particles upon contact with water and by having a higher rate of solution than the powder used to form the agglomerates.

7. A water treating product consisting essentially of porous agglomerates composed of a number of irregularly shaped, loosely adhering powder particles essentially comprising sodium triphosphate, said'particles being bound together to form said agglomerates by means of a hu- Humidify and ag- .tetraphosphate. said particles being bound together to form said agglomerates by means of a humidified sticky film of said tetraphosphate. said agglomerates being characterized by having the property of rapidly disintegrating into finely divided particles upon contact with water and by having a higher rate of solution than the powder used to form the agglomerates.

9. A water treating product consisting essentially of porous a'gglomerates composed of a number of irregularly shaped, loosely adhering powder particles essentially comprising" sodium decaphosphate, said particles being bound together to form said agglomerates by means of a humidified sticky film of said decaphosphate.

said agglomerates being characterized by having the property of rapidly disintegrating into finely divided particles upon contact with water and by having a higher rate of solution than the powder used to form the agglomerates.

FINDLEY E. HUBBARD. CAMPBELL R. McCULLOUGI-l. 

